Thread: Mitred joints - opening Pandora's Box

Originally Posted by The Spin Doctor

Getting back to mitres.

The only thing I can think that could cause them to pop is if one board has tension in it and through the seasons tries to warp. If I'm not mistaken that is a single wide board which has much higher risk of warping than a glued up board. If there is persistent Longterm tension, there's a high risk of the glue eventually failing. It think you said you were using hyde glue? Never used it myself but I think it can creep can't it? If so, then with constant stress on the joint it will probably let go.

The only other way I think the mitre could fail is if the board are quite thick. Mitres tend to open when the wood over time shrinks and swells. The toe of each mitre is pulled away from each other as the wood swells. Works the same on inside mitres but it's the heals that pull apart. It's why as joiners we never mitre inside corners, they're always coped. On outside mitres on thick skirting I'll often plane some of the mitre off the heal to relieve future stress.

These are stable boards. Quartersawn. Very controlled when re-sawn. No inner tensions that I could note.

I wrote about hide glue earlier: "hide glue is reversible if you need to make repairs, and old glue does not need to be removed - just add more glue. It dries clear and does not affect any finishes (unlike yellow glue). Cleans up in water. It does not creep. It is as strong as epoxy (according to Don Williams at the Smithsonian)."

This is a very stable glue, with many positive characteristics.

Note that mitred joinery in boxes and cases is very common. Much is, and much is not reinforced. Either way, if movement took place, all the reinforcement in the world would not prevent the joins opening up. But glue is stronger than wood, and sized joins are strong mitres. In the end it is more like joining panels.

Regards from Perth

Derek

Originally Posted by The Spin Doctor

Whos Warren?

Spent a few years at sawmill creek and came across a few arrogant dicks. One in particular thought he was god, he certainly was old enough to be, even had his own gaggle of disciples, but warren isn't ringing any bells.

Warren is reputed to be an expert woodworker. He only works with hand tools. Only David has ever seen his work, in a few photos. No one else has seen his work. He is critical of everyone, of all contributions, and only the work and tools of the 18th century are acceptable. All else is despised. Fun guy.

Regards from Perth

Derek

Originally Posted by The Spin Doctor

Whos Warren?

Spent a few years at sawmill creek and came across a few arrogant dicks. One in particular thought he was god, he certainly was old enough to be, even had his own gaggle of disciples, but warren isn't ringing any bells.

Warren is a pro who works by hand only - he legitimately doesn't have much of anything in his shop other than hand tools and whatever production work he's doing. He's wildly intelligent, extremely deep and experienced and has been at it for something like 50 years. What he does on a day to basis ranges from boring, repetitive (but not necessarily easy) to contributions to period work sold from places like Andersen and Stauffer.

he doesn't offer much about what he's doing - I think there are varied reasons from the production work not being that interesting to probably not having permission from clients to show it in the first place.

And, I believe from talking to him, he does believe that correcting bad or subpar information is helpful. But it will definitely leave you as a reader with the obligation to figure out what he means as the descriptions are often brief and sometimes when you receive the correction, you have to cool off and think about whether or not you can relax and figure out what he's talking about despite having red cheeks.

He is unique, not unfriendly in person, and for folks who don't offer up too much and who call out errors (either clear or just in their opinion) don't come across well online. I think a lot of folks who give a lot of advice or just insistent advice don't know how they're perceived by at least some % of readers. People who aren't beginners (warren doesn't bother beginners unless they're making really foolish bold false statements) and who don't like being corrected could easily feel like warren is too critical - especially if the objective is to have some kind of friend group or posse where you become exempt from correction.

Not sure who the older person you mention might be. Could be one of several. There was at least one person who was good enough that he would eventually be seated at the right hand of the "father of all makers" if there was maker heaven.

What will hold your job together with hide glue Derek is the tight true quality of your joins . They look very crisp so should hold well. Unless some form of neglect happens as I was saying before.

My thoughts and beliefs in HG .

Fresh hide glue hot from a glue pot has a better reputation than liquid hide glue for strength. I learned that from hanging around the luthiers forum ANZLF and on this forum when I was building an acoustic guitar. Those guitar builders analyze stuff to death like that and last time I paid attention they recommended not touching the liquid stuff.

Ive never used liquid HG but have spent many years using Hot HG from pots and bottles with Antique restoration and building stuff from new.
If you had to repair a hide glue joint and try to get it apart by reversing it the trouble and effort is huge to get heat and moisture into the joint to do that. It normally requires piping in steam with drilling holes and inserting brass tubes connected to rubber tubes and boiling lidded pots of water and is easier on things like chair joints than something like your boxes. Ive tried that a few times on chairs and heated and soaked a Cuban Mahogany veneered bureau flap once to get its 18th century quality flame Cuban veneer. After getting some of the chair repairs apart I always considered from that point that a saw may be easier way of getting them apart on future jobs.

The reversibility beauty of HG is when the application is veneering. The need to reverse is used all the time in situations like lifting off recently laid veneer so a cross banding can be applied to edges. Or slicing and lifting out sections for stringing. Or lifting an overlapped section for a join that has been created by slicing through the two layers. The HG job can be days old . Even a week or more and there is still enough moisture left in the job to make reversing simple and easy. Reversing a year or more old tight joint though and it may as well be epoxy . Its not going to be easy at all to get apart cleanly unless a good hit with a mallet and padding can knock it free IMHO.

Rob

Thanks again Rob.

For reference, testing done by Fine woodworking showed that Old Brown Glue was overall 3% stronger than Hot Hide Glue.

Regards from Perth

Derek

Originally Posted by auscab

Fresh hide glue hot from a glue pot has a better reputation than liquid hide glue for strength. I learned that from hanging around the luthiers forum ANZLF and on this forum when I was building an acoustic guitar. Those guitar builders analyze stuff to death like that and last time I paid attention they recommended not touching the liquid stuff.

Rob

You're on the money. The higher end the acoustic guitar, the more glue hardness is favored as it's seen as necessary to transmit vibrations (unsure how much of this has been double blind tested in large samples!) .

I've made only solid body guitars generally with TB1 and as thin of joint lines as possible, so my opinion doesn't really count (shop and basement aren't typically warm enough to use hide glue). My ears have been assaulted by conversations about a high hardness hot hide glue, though.

Interestingly, people think they can hear all kinds of things in solid bodies and will say things like "you can't make a good guitar with titebond" and then gush about a gibson guitar that was made using titebond.

I've seen factory videos of gibson now putting tops on (custom shop?) solid body guitars with a big thick layer of liquid hide glue just to be able to tell people the higher end guitars are hide glue. I get it, it's a business, but it's a bit of a cringer! Their neck joints can be really loose (to aid jigging) with the deficit made by a pretty significant pool of hide glue - hopefully that is high strength hot stuff.

Originally Posted by D.W.

Warren is a pro who works by hand only - he legitimately doesn't have much of anything in his shop other than hand tools and whatever production work he's doing. He's wildly intelligent, extremely deep and experienced and has been at it for something like 50 years. What he does on a day to basis ranges from boring, repetitive (but not necessarily easy) to contributions to period work sold from places like Andersen and Stauffer.

he doesn't offer much about what he's doing - I think there are varied reasons from the production work not being that interesting to probably not having permission from clients to show it in the first place.

And, I believe from talking to him, he does believe that correcting bad or subpar information is helpful. But it will definitely leave you as a reader with the obligation to figure out what he means as the descriptions are often brief and sometimes when you receive the correction, you have to cool off and think about whether or not you can relax and figure out what he's talking about despite having red cheeks.

He is unique, not unfriendly in person, and for folks who don't offer up too much and who call out errors (either clear or just in their opinion) don't come across well online. I think a lot of folks who give a lot of advice or just insistent advice don't know how they're perceived by at least some % of readers. People who aren't beginners (warren doesn't bother beginners unless they're making really foolish bold false statements) and who don't like being corrected could easily feel like warren is too critical - especially if the objective is to have some kind of friend group or posse where you become exempt from correction.

Not sure who the older person you mention might be. Could be one of several. There was at least one person who was good enough that he would eventually be seated at the right hand of the "father of all makers" if there was maker heaven.

Sounds like he'd be on my block list in about 5mins. I don't suffer a-holes anymore. We all have our bad days but if it's a constant - no, they disserve to be ignored.

Can't talk about other trades but woodwork is an interesting one for what's right and what's wrong... George is the dick I was talking about on Saw Mill, and his wanna be disciples. When I first got to Woodwork Forums in 2005 I was at that time pretty experienced as a furniture maker and reasonably well respected in my town. I only worked for other woodworkers, doing the stuff they didn't trust their employees to do, or couldn't... I was kinda like this Warren fella, in that I thought there was only one way to do things... I can remember throwing my arms in the air reading the things Derek used to write. And say: What are you thinking!!!

Some years later I had a pretty bad break down and was totally fed up with woodwork in QLD (this place is a desert for good work unless you like chipboard and laminate and 80% of the bosses a-holes) and walked away. I came back to it as a hobby quite a few years later simply because I loved the woodwork itself, even if it wasn't my job at that time... In all my time I've met a fair few "superstars" of the woodwork and woodturning world and read their blogs and what have ya and they've never taught me a thing about woodwork that I pretty much didn't already know. There is one fella that did. I mostly lurked when I drifted back into woodwork and watched and read his stuff here and at Saw Mill. He's the only one to teach me anything. And in general terms its: there's many many ways to accomplish your projects and there is no absolute right way to do something. If you're not enjoying it, you're doing something wrong... And that is Derek. He has a lot of "experts" take pot shots at him but he carries on, in his way and most importantly enjoys it. I relearned how to enjoy the craft and F$%k the rest. I may do things differently than he does but I no longer disagree with how he or anyone goes about making things, it's not the point. Enjoy it and take risks. So ya, Warren would be blocked in less than 2 mins actually. He sounds like a real buzz kill, and life is too short, especially when you're nearly 60.

I kind of follow patterns, and I'm an experimenter - an observer. I'm sure my static with derek wouldn't last forever.

George is probably not liked by folks who are just kind of idling along in the boat, so to speak, but he is a fantastically generous and honest person. I made mistakes over the years thinking that whatever I uncovered (which almost always ends up being similar to something published a while ago - there's nothing new) would be interesting to other people. But most folks want to see what you made and they might be interested in seeing how you make it.

And then perhaps not approve of your methods because they don't seem official enough.

The forums don't do a good job, and probably can't, of putting people through the human coin sorter to end up talking to or reading from the folks that they like.

I talk to george often. I've met warren in person and don't talk to him generally between the (so far only a few) visits when he's in town. If I'd have met him in person first, I'd have known he wasn't a troll. We generally, I guess, think the person we are "in person" will just come across online. It just doesn't actually happen.

Knowing now that I talk to george often, please don't interpret that as anything to do with your opinion or me thinking "oh, it's wrong, you're wrong!". I don't go there - we all get to have our own opinions and George being my friend doesn't mean everyone has to like him. I talk to George that's George and we don't often talk about things we're making - as in, I'm not talking to George the guy I have to learn everything from about making - that would be pointless). I hide what I'm making so that I can come up with my own stuff and do it my own way and then if I lose interest, then I might show him what I made months ago - but that's not usually the case.

It took all of about 16 years before meeting warren. I figured he didn't want to be bothered, so I didn't bring it up - if you discussed much with him online, you'd probably figure the same as me. He has a friend who lives near where I do - could've avoided a lot issues earlier. Totally different experience in person, still the same guy, but no time to sit and stew and anticipate something bad.

(you're right about the george disciples - there were some who really weren't interested in learning from him - they wanted to be wowed and entertained. I would often say he's probably one of the finest makers alive, but I would say that because it's true - I wasn't sure that I wanted to learn anything from him at first, but he spotted something I made, asked to call me, and then told me how I could make it better. It was a pass or fail kind of thing and an obligation to me at the time - but I learned more at once about what to do than I'd learned in 4 or 5 years prior. There were plenty of people who hated him because he wasn't the equivalent of C. Schwarz or some other enthusiasts and people are invested in their personality. You can be right, for example, but if you say paul sellers is lacking substance, a large percent of people who love paul sellers will suddenly have a serious distaste for you. And some will tell you that you said they were stupid because they like paul sellers - it can become bizarre).

Getting back to the mitres ......

My first response was my opinion on it - doesn't matter what anyone else really thinks. They can be glued if it doesn't work, they can be repaired later. Very little out on the open market meets our battleship belt armor standards - so if that stuff is appreciated, it's ok for us to have something that's repaired once in a while.

I thought I would resurrect this thread with the results of a quick and dirty experiment.

I recently was involved in a similar discussion about whether wood picture frames should be splined. The usual arguments ensued. I decided to do a little test to settle the matter for all time.

I made some partial frames of scrap softwood 9 x 21 mm in section. Mitred them to 45 degrees and planed the joint surfaces smooth on my mitre jack. Here are four pieces planed together.
CF95FDB7-6568-492D-89CF-05F7B0B9E02A_1_105_c.jpeg

Then I glued the frames together with TiteBond Original (a PVA glue) using just a rub-joint method and plenty of glue. I let them sit for an hour and then kerfed two of the frames with a hand saw and glued in white oak splines the thickness of the kerf, about 0.7 mm. I clamped the faces of the kerfed frames, let them it overnight, and cleaned them up in the morning.

EE8D9428-267F-4961-883B-B19A7C3E6D42_1_105_c.jpeg

Then I hung a bucket from the middle of the "U" and clamped that below my bench vise.

8A88108C-B42D-428C-A9B9-0DC67D27E932_1_105_c.jpeg

And filled the bucket with weights of known mass confirmed with a kitchen scale. I used barbells, bit of cast iron, and cans of dog food, black beans, lentils, and garbanzo beans. I added weights until the frame failed at one or both joints.

B1F1FE7C-B0C6-4334-BD91-D9EB3ACCFD67_1_105_c.jpeg


The result was that the unsplined joints failed at about 31 pounds/14 kg. The splined mitres failed at about 55-60 pounds/25-27 kg. A little less than twice as much. The splined joints failed when the spline itself cracked in half. A thicker spllne would have been stronger.

As I said, quick and dirty but perhaps a place to start. My take-aways were:

The frame pieces I used were flimsy. A normal picture frame would have more glue surface and be even stronger, suggesting that unless one had a large picture plus glass and a thin frame a spline would not be necessary. But a large picture and small frame would benefit from a spline.

I did not assess the effect of stress on creep and joint failure. It might be that PVA glue would fail with time at lower weight. Don't trust the absolute numbers I found.

What else should one consider?

I've been doing plain mitres on boxes for yonks, with hide glue and PVA and never had a problem or a return. I'll do decorative feathers or splines for a design feature. Richard Vaughan's work on glued joints convinced me. Here is a more recent video supporting the glued mitre strength, with a note that there are caveats in the video. This Simple Joint is Stronger Than a Dovetail! - YouTube. I don't think it has been posted before.

Originally Posted by mic-d

I've been doing plain mitres on boxes for yonks, with hide glue and PVA and never had a problem or a return. I'll do decorative feathers or splines for a design feature. Richard Vaughan's work on glued joints convinced me. Here is a more recent video supporting the glued mitre strength, with a note that there are caveats in the video. This Simple Joint is Stronger Than a Dovetail! - YouTube. I don't think it has been posted before.

Thanks, mic-d.

I am such an iconoclast, and love it when someone rattles our paradigms. Mind you, as the presenter said, we must consider the direction of the forces involved and seasonal movement and a few other issues. Whilst this video does not provide definitive proof, it demands we rethink some of our fundamental "truths".

Originally Posted by John Samuel

Thanks, mic-d.

I am such an iconoclast, and love it when someone rattles our paradigms. Mind you, as the presenter said, we must consider the direction of the forces involved and seasonal movement and a few other issues. Whilst this video does not provide definitive proof, it demands we rethink some of our fundamental "truths".

I would say I'm an iconoclast too John. I follow the scientific method and abandon any position that the wind of evidence doesn't blow towards. If we separate strength and longevity of joints and focus just on the strength of these corner joints then I thinks the video is a logical result. We like to bang on about how glue is stronger than wood so if we construct a joint in a fashion that presents the strongest arrangement of wood and the maximum glue area, then that joint should be the strongest. This seems to be borne out by the video *with the exception of the box joint - which seems likely to be from glue starvation*. To say it a different way; If the joint is engineered in such a way that the arrangement of wood makes the glue line break first that's got to make the strongest joint.